As defined by the RDoC Social Processes Workshop, affiliation is the engagement in positive social interactions with others. The desire to affiliate has been described as a fundamental human motivation. However, impairments in the drive to affiliate occur across multiple clinical disorders and these affiliative impairments have devastating consequences for individuals, their family members, and society. Despite the major clinical significance of impairments in social affiliation, the factors that contribute to affiliative impairment are poorly understood. We propose a multi-method assessment of a large and diverse clinical sample to examine how social affiliative deficits are associated with a) the social regulation of neural systems relating to emotion as assessed through a novel fMRI paradigm for studying the in vivo social regulation of emotion in the context of affiliative relationships, b) neural processes associated with social reward, c) learning of the positive affective value of others, and d) behavioral affiliative skills. Consistent with the RDoC, this application will include assessment of affiliation processes across units of analyses including circuits, behavior, and self-report within a transdiagnostic sample of individuals with psychotic disorders. With regard to the study of neural systems, a powerful mechanism that may underlie the motivation for social contact is the social regulation of emotion, particularly the social regulation of threat responding. We propose the use of a novel paradigm to create affiliative relationships within the lab and subsequently will examine how this affiliative relationship regulates emotional responding to a stressor (a key function of affiliative relationships) within an fMRI scan. Specifically, we will examine the hypothesis that affiliative deficits are associated with the failure of social contact to down regulate neural activity in the context of a stressor. In addition to the benefits that affiliation provides when responding to threat, the motivation for social relationships may derive from activation of neural systems involved in reward. We will also explore the contribution of reward circuits to affiliative impairment using both social and monetary reward paradigms. Beyond neural responding, the proposed study will examine how individuals form behavior-based impressions of others in ways that may facilitate or impede social affiliation. We will examine the hypothesis that deficits in affiliation are associated with impairments in the ability to use behavior-based person information to form positive impressions concerning the affective value of others in the social environment. Finally, behavioral social skills form the basis for effective communication and are thought to be critical to social competence. We will examine the hypothesis that impairments in social affiliation are specifically related to deficits in behavioral affiliative skills. The proposed study will provide an integrative perspective to advance our understanding of the neural and behavioral factors that give rise to impairments in social affiliation within clinical populations and this research will provide insights that will inform the development of interventions to address such impairments in affiliation.